MDCs at the Ml stage (i.e., the NH₃ (1,1) emission is roughly concentrated around the column density peaks). The background is pseudo three-color images of each field, with Spitɀer 8, 4.5, and 3.6 µm emission colored in red, green, and blue, respectively. The contours of H₂ column density and NH₃ (1,1) integrated emission are over-plotted with green and orange, respectively. Cyan and magenta crosses mark the positions of any H₂O masers or radio continuum sources, respectively. The starless, IR-quiet, and IR-bright MDCs are shown as pink dashed, red dashed, and red solid ellipses, respectively. More figures are showed in Appendix C.